In a conventional picture data processing apparatus of this type, picture information is encoded into picture data so that moving pictures are transmitted with high efficiency.
More specifically, in the conventional apparatus, picture information supplied successively thereto is divided into predetermined blocks, and a motion vector is detected for each block according to a block matching method.
In addition, in the apparatus, the picture data of the preceding frame (coming one frame before) is subjected to motion compensation according to the results of detection of the motion vectors, and the picture data thus subjected to motion compensation is subtracted from the picture data supplied, to provide difference data.
With the apparatus, the quantity of the picture data handled is reduced in comparison with a case where the picture data is directly transmitted by utilizing the inter-frame correlation of moving images.
The difference data is then subjected to discrete cosine transform and to variable-length coding.
As a result, the amount of data to be transmitted is reduced with respect to higher-order frequency components, and the picture data is efficiently transmitted as much as possible.
The variable-length coded data is transmitted through a predetermined buffer memory, so that moving picture data can be transmitted within permissible transfer rate of a transmission system.
In the case where moving pictures are transmitted by performing the discrete cosine transform block by block, the picture displayed after decoding appears foggy at a block including an edge.
That is, when the picture data are coded in the above described manner, then the resultant picture appears greatly deteriorated in picture quality.